Final answer:
Protein Kinase C (PKC) gets activated by DAG and Ca2+ after the enzymatic action of phospholipase C on PIP2, leading to cascades of phosphorylation that regulate various cellular responses including metabolism, growth, and gene transcription.
Step-by-step explanation:
Protein Kinase C (PKC) is an enzyme that plays a crucial role in signal transduction pathways. It is activated as a result of the cleavage of phosphatidylinositol 4,5-bisphosphate (PIP2) by the enzyme phospholipase C. This process generates diacylglycerol (DAG) and inositol triphosphate (IP3), which function as second messengers. DAG remains in the plasma membrane and activates PKC, which then phosphorylates serine and threonine residues on specific target proteins, influencing their function. Concurrently, IP3 diffuses into the cytoplasm to bind to ligand-gated calcium channels on the endoplasmic reticulum, prompting the release of Ca2+ ions. These ions, in conjunction with DAG, activate PKC, leading to a phosphorylation cascade that results in various cell-specific responses. The action of PKC includes phosphorylation of the inhibitor protein IK-B; once phosphorylated, IK-B can no longer bind NF-KB, thus allowing NF-kB to enter the nucleus and initiate RNA transcription, impacting cellular metabolism and growth.